GB2214362A

GB2214362A - Detachable open/short testing fixture device for testing P.C. Boards

Info

Publication number: GB2214362A
Application number: GB8800729A
Authority: GB
Inventors: Gab Hsu
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-01-13
Filing date: 1988-01-13
Publication date: 1989-08-31
Also published as: GB8800729D0

Abstract

A detachable open/short testing fixture device with spring contact probes for testing the circuits on printed circuit boards comprises a lower and upper probe-board sets (150, 160). The lower probe-board set (160), for connecting pads on the printed circuit board to a piece of testing equipment, has first and second insulated boards (4, 5), and a first transmitting board. The upper probe-board set (150), for forming a connection between the printed circuit board and the lower probe-board set (160), has third and fourth insulated boards (1, 2), and a second transmitting board (3). A plurality of spring contact probes (72, 71) are slidably retained in the lower and upper probe-board sets (150, 160) for forming connection therebetween. Moreover, a plurality of square pins (73), connecting wires (74) and connectors (83) are provided in the device for connecting the lower probe-board set (160) to a base. <IMAGE>

Description

TITLE: DETACHABLE OPEN/SHORT TESTING FIXTURE DEVICE FOR TESTING P.C. BOARDS The present invention relates to a detachable open/short testing fixture device mounted on an equipment for testing the circuits on printed circuit boards (P.C. boards), and more particularly relates to a detachable open/short testing fixture device with detachable spring contact probes.

Owing to the improvement of electronical products and semiconductive components, the circuits on the (P.C. boards) are getting increasingly complicated, and various types of open/short testing equipment and probes for testing circuits on the P.C. boards have been developed in order to help alleviate testing problems. However, the open/short testing equipment and probes still possess some drawbacks. A conventional open/short testing fixture as shown in Fig. 8 comprises a probe 120 fixed on an insulated board 111 and a connecting wire 112 that forms a connection between the end of the probe 120 and the terminal of a connector 114. Moreover, conventional probes 120, as shown in Fig. 9, comprise a contact head 121, a plunger 122, a spring 123 in contact with the plunger 122, a barrel 124, and a receptacle 125 with a pin 126, which encases the barrel 124.

Previously, each type of P.C. board required its own open/short testing fixture. In addition, individualized testing boards were required for each type of P.C. board. A one-on-one testing method is necessary. The drawbacks of the prior arts are as follows: (1) It is rather difficult to repeatedly use the testing materials, for example probes, connecting wires, and connectors.

(2) The costs of testing materials are high and the choices of the testing points on P.C.

board for reducing costs are rather time consuming.

(3) It is impractical for medium-size P.C. board manufacturers to set up a special open/short testing fixtures for only a few orders of individualized methods.

(4) The open/short testing fixtures occupy much space and cause storage problems due to the non-uniform shapes thereof.

(5) The process of setting up open/short testing fixtures is time-wasting, for example the choice of testing points, connecting wires, assemble of the desired P.C. boards on the open/short testing fixture, and the connections between connectors and open/short testing fixture. Further, - a skilled technician is required to operate the process.

There are some kinds of open/short testing fixtures called universal open/short testing fixtures which can solve the above-mentioned drawbacks, but the cost of the universal open/short testing fixtures is too high, and they are not suitable to general products.

The present invention is therefore to provide a detachable open/short testing fixture device with spring contact probes and which can be separated into two parts and merely requires to be altered an upper probe-board set as different kinds of P.C. boards are tested without wasting a lot of time.

The present invention provides a detachable open/short testing fixture device with spring contact probes which is easily assemblied for only a lower probe-board set requiring connecting wires and connectors.

The present invention provides a detachable open/short testing fixture device with spring contact probes which has no more sorting testing points problems and can attain the goal of total inspection.

The present invention provides a detachable open/short testing fixture device with spring contact probes which greatly reduces the manufacturing cost and which reduces the storage volume of the probe boards.

The present invention provides a detachable open/short testing fixture device with spring contact probes, the probes can be used repeatedly by turned off from upper probe-board set.

The present invention provides a detachable open/short testing fixture device with spring contact probes, which can test more complicated circuits easily.

The present invention provides a detachable open/short testing fixture device with spring contact probes, which can act as an universal open/short testing fixture but just employ the open/short testing fixtures with 2048, 4096 or 5248 testing points.

The present invention provides a detachable open/short testing fixture device which is simple to manufacture.

This invention will become more apparent from a careful reading of the detailed description provided hereinafter, with appropriate reference to the attached drawings, showing a preferred embodiment of the present invention.

In the drawings: Fig. 1 is a perspective view of a detachable open/short testing fixture device for testing printed circuit boards in accordance with the present invention; Fig. 2 is an exploded view of the detachable open/short testing fixture device of Fig. 1; Fig. 3A is a schematic view of an arrangement of probe holes on insulated boards for a detachable 6pen/short testing fixture device with 5248 testing points; Fig. 3B is a schematic view of an arrangement of pads and plated through holes on transmitting boards for a detachable open/short testing fixture device with 5248 testing points; Fig. 3C is a schematic view of the connections between pads by copper strips which are positioned diagonally for a detachable open/short testing fixture with 5248 testing points;; Fig. 4A is a partial perspective view of pads 33, 34, 37, 38 illustrating connections by copper strips 35, 35' on both upper and lower sides of the first transmitting board 3 of Fig. 3C; Fig. 4B is a partial perspective view of pads similar to Fig. 4A, but illustrating a plurality of square pins 73 welded on the lower side of the transmitting board; Fig. 5A is a schematic view of arrangement of pads on the lower side of first transmitting board with variable distances between columns and rows; Fig.SB is a schematic view of the connections between PTHs. 33 and pads 34 by copper strips 35 for a detachable open/short testing fixture device with 2048 testing points; Fig. SC is a schematic view similar to Fig. 5B, but for a detachable open/short testing fixture device with 4096 testing points; Fig. 6 is a cross-sectional view of a detachable open/short testing fixture device illustrating a connecting path in accordance with the present invention; Fig. 7 is cross-sectional view similar to Fig. 6, but illustrating that probe hole 21 on second insulated board 2 does not align with probe hole 11 on first insulated board 1; Fig. 8 is an exploded view of a conventional open/short testing fixture device; and Fig. 9 is an exploded view of a conventional spring contact probe.

With reference to the drawings and particularly to Fig. 1 thereof, it can be seen that a detachable open/short testing fixture device with spring contact probes mounted on equipment in accordance with the present invention comprises a plurality of probes 71, an upper probe-board set 150, a lower probe-board set 160, a plurality of connectors 83 and an insulated base 8 of the detachable open/short testing fixture device.

The invention relates to such an open/short testing fixture in which the upper probe-board set 150 is altered for testing another type of P.C. boards, and the lower probe-board set 160 combines with the base 8 during all the testing processes.

Referring to Fig. 2, the upper probe-board set 150, for forming a connection between the P.C. board and the lower probe-board set 160, comprises a first insulated board 1, a second insulated board 2, and a first transmitting board 3. Owing to the function of upper probe-board set 150, the arrangements of probe holes on first and second insulated boards 1, 2, and the arrangement of pads and plated through holes (PTHs.) on first transmitting board 3 are designed according to the P.C. board to be tested and, moreover, depend on the types of the open/short testing fixture devices being used. The arrangements of probe holes, pads and PTHs. are fully detailed in the specification hereinafter.

The lower probe-board set 160 which acts as a universal interface for conducting pads on the P.C.

board to be tested to the equipment comprises a third insulated board 4, a fourth insulated board 5, and a second transmitting board 6. Owing to the function of lower probe-board set 160, pre-set arrangements of the probe holes on third and fourth insulated boards 4, 5, and the arrangement of pads and PTHs. on second transmitting board 6, respectively, are designed according to the types of the open/short testing equipment, for example with 2048, 4096 or 5248 testing points. First and second transmitting boards 3, 6 are P.C. boards with double sided layout.

Located holes indicated as 12, 22, 32, 42, 52 and 62 are provided on each corner of all said boards 1 to 6, respectively. Holes 12, 22, 32, 42, 52 and 62 are aligned so as to combine all said boards 1 to 6 together by supporting rods 75 with nuts 76 and two Eshaped rings 77.

For the open/short testing equipment with 5248 testing points, the arrangement of the probe holes 11 distributed on first insulated board 1 corresponds with that of pads on the P.C. board to be tested. The arrangement of spaced probe holes 21 distributed on second insulated board 2 is shown in Fig. 3A. The interval between each pair of spaced probe holes 21 is 2.54mm. The arrangement of the spaced square pads 33 and PTHs. 31 shown in Fig. 3B distributed on the upper side of first transmitting board 3 is the same as that of the spaced probe holes 21 on the second insulated board 2.

According to the above-mentioned interval of 2.54mm, about 10496 probe holes, PTHs. and pads are distributed on a 320mm x 210mm board. The connection of copper strips 35, 35' provides a detachable open/short testing equipment with 5248 testing-points which can test a P.C. board with 10496 pads. Furthermore, there are a plurality of pads not utilized on P.C. boards because of limitations set by international I.C.

standards, for example, as shown in Fig. 3C, light dots indicate positions of PTHs. at intervals of 2.54mm, and heavy dots 310 indicate the possible positions of the pins of I.C. with 16 pins.

Taking pads 33, 33', 34 and 34' as an exemplary unit, it can be seen that pads 33 and 34 are connected on the upper side of first transmitting board 3 by copper strip 35, as shown in Fig. 4A; likewise, the other two pads 33', 34' are also connected diagonally by copper strip 35', indicated in dotted lines, on the lower side of first transmitting board 3 in such a way that both of the connecting lines are oriented diagonally to each other.

As to the lower probe-board set 160, the arrangement of spaced probe holes 41, 51 on third and fourth insulated boards 4, 5 is such that the interval between each pair of probe holes 41, 51 of the same row is 2.54mm and the interval between each pair of probe holes 41, 51 of the same column is 5.08mm; that is, about 5248 probe holes are distributed on a 320mm x 210mm board. The arrangement of pads 64 and PTHs. 63 on the second transmitting board 6 is similar to that of holes 41, 51 on third and fourth insulated boards 4, 5, but pads 64 and PTHs. 63 on second transmitting board 6 are not in alignment with holes 41, 51 on third and fourth insulated boards 4, 5. A plurality of square pins 73, in this case 5248 pins, are welded in each PTHs. 63 on the lower side of second transmitting board 6 for connecting second transmitting board 6 and connecting wires.

In addition to the above-mentioned fixture device, the testing fixture device with 5248 testing points can be made by above-mentioned upper probe-board set 150 only. A plurality of square pins 73, in this case 5248 pins, are welded in each of the PTHs. on the lower side of first transmitting board 3, as shown in FIG.

4B. Further, square pins 73 are connected with connecting wires 74.

For an open/short testing equipment with 2048 testing points, the arrangement of probe holes 11, 21 on first, second insulated boards 1, 2 and PTHs. 31, pads 33 on the upper side of first transmitting board 3 corresponds with that of pads on P.C. board to be tested. The arrangement of pads 34', on the lower side of first transmitting board 3 is similar to Fig. 5A; that is, the interval between each pair of pads 34' of the same row is 3.81mm and the interval between each pair of pads 34' of the same column is 8.89mm.

Referring to Fig. 5B, dots indicate possible positions of PTHs. 31 on the upper side of first transmitting board 3, and crosses indicate positions of pads 34' on the lower side of first transmitting board 3.

Moreover, PTHs. 31 are connected with pads 34' by copper strips 35'(shown in dotted lines).

The arrangement of spaced probe holes 41, 51 on third and fourth insulated boards 4, 5 corresponds with that of pads 34' on the lower side of first transmitting board 3. The arrangement of pads 64 and PTHs. 63 on second transmitting board 6 is similar to that of pads 34'on the lower side of first transmitting board 3, but PTHs. 63 on second transmitting board 6 are not in alignment with pads 34' on the lower side of first transmitting board 3. Furthermore, a plurality of square pins 73 are welded in each of the PTHs. 63 on the lower side of the second transmitting board 6.

For an open/short testing equipment with 4096 testing points, the arrangement of probe holes 11, 21 on first and second insulated boards 1, 2 and PTHs. 31 pads 33 on the upper side of the first transmitting board 3 correspond with that of pads on the P.C. board to be tested. The arrangement of pads 34' on the lower side of first transmitting board 3 is similar to Fig.

5A; that is, the interval between each pair of pads 34' of the same row is 2.54mm and the interval between each pair of pads 34' of the same column is 6.6mm.

Referring to Fig. 5C, dots indicate the possible positions of PTHs. 31 on the upper side of first transmitting board 3, and crosses indicate the positions of pads 34' on the lower side of first transmitting board 3. Moreover, PTHs. 31 are connected with pads 34' by copper strips 35' (shown. in dotted lines).

The arrangement of spaced probe holes 41, 51 on third and fourth insulated boards 4, 5 corresponds with that of pads 34' on the lower side of first transmitting board 3. The arrangement of pads 64 and PTHs. 63 on second transmitting board 6 is similar to that of pads 34' on the lower side of first transmitting board 3, but PTHs. 63 on second transmitting board 6 are not in alignment with pads 34' on the lower side of first transmitting board 3.

Furthermore, a plurality of square pins 73 are welded in each of the PTHs. 63 on the lower side of the second transmitting board 6.

With particular reference to Figs. 6 and 7, respective, connecting paths in accordance with the present invention will be described hereinafter in order to point out the significance of the present invention. In accordance with the present invention, spring contact probe 71 comprises a contact head 711, a spring 712 and a tip 713, all of which can be utilized repeatedly. Moreover spring contact probe 71 can be used to easily test more complicated circuits due to the fact that outer diameter of spring contact probe 71 is less than that of a conventional probe shown in Fig. 9.

The diameter of the probe holes is larger than that of spring contact probes, and the diameter of PTHs. is smaller than that of spring contact probes.

The contact head 711 and the tip 713 of spring contact probe 71 are respectively slidably retained in probe holes 11 and 21, and are spring-loaded against each other; so that spring contact probe 71 is held by pad 90 to be tested and by PTHs. 33, for forming connection between the P.C. board to be tested and the upper probeboard set. In a like manner, another spring contact probe 72 contacts pads 34', 64 on either end thereof, for forming connection between the upper probe-board set and the lower probe-board set. Moreover, connecting wires 74 connects square pins 73 mentioned above and connectors 83, as shown in Fig. 6.

Furthermore, the connecting path of another embodiment of a testing equipment with 5248 testing points, shown in Fig. 7, is similar to that shown in Fig. 6; but illustrating that probe hole 21 on second insulated board 2 does not align with probe hole 11 on first insulated board 1. The practicability of connecting path shown in Fig. 7 is that the difference between two center axes of probe holes 11 and 21 is 1.27mm at most, because the interval between each pair of probe holes is 2.54mm.

So obviously, a transmission network is formed between the P.C. board to be tested and the open/short testing equipment by two connecting paths, shown in Figs. 6 or 7 of two points which. are in short circuit on P.C. board to be tested.

As various possible embodiments might be made of the above invention without departing from the scope of the invention, it is to be understood that all matter herein described or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense. Thus it will be appreciated that the drawings are exemplary of a preferred embodiment of the invention.

Claims

CLAIMS:

1. A detachable open/short testing fixture device with spring contact probes mounted on equipment for testing circuits on a printed circuit board comprising: a. a lower probe-board set, for conducting pads on said printed circuit board to be tested to said equipment, comprising a third insulated board, a fourth insulated board, and a second transmitting board; b. an upper probe-board set, for forming a connection between said printed circuit board and said lower probe-board set, comprising a first insulated board, a second insulated board, and a first transmitting board; c. a plurality of spring contact probes slidably retained in said upper and lower probe-board sets for forming connection therebetween; d. a plurality of square pins welded in each of plated through holes on a lower side of said second transmitting board;.

e. a plurality of connecting wires for connecting with said square pins; and f. a plurality of connectors for connecting said connecting wires to a base.

2. A detachable open/short testing fixture device as set forth in claim 1, wherein: a plurality of probe holes are distributed on said first, second, third and fourth insulated boards; and a plurality of pads and said plated through holes are distributed on said first and second transmitting boards.

3. A detachable open/short testing fixture device as set forth in claim 1, wherein: a diameter of said probe holes is larger than that of said spring contact probes; and the diameter of said plated through holes is smaller than that of said spring contact probes.

4. A detachable open/short testing fixture device as set forth in any of claims 1 to 3, wherein a detachable open/short testing fixture device has 5248 testing points.

5. A detachable open/short testing fixture device as set forth in any of claims 1 to 3, wherein a detachable open/short testing fixture device has 2048 testing points.

6. A detachable open/short testing fixture device as set forth in any of claims 1 to 3, wherein a detachable open/short testing fixture device has 4096 testing points.

7. A detachable open/short testing fixture device substantially as hereinbefore described with reference to the accompanying drawings.